For environmental and economical reasons, it is essential to maximize the production of lumber from each log. To achieve the best possible wood yield from a log, the log has to be suitably positioned in relation to the stationary sawing members of a sawing apparatus in which the log is fed, both with respect to the angular position of the log about its longitudinal axis and the orientation and position of the longitudinal axis of the log.
Modern log-positioning machines are computer-assisted. It is known to scan the front face of the log with an optical scanner, and to subsequently analyze the log image by means of a computer program. The computer can command a log turning apparatus to adjust the angular position of the log about its longitudinal axis, according to a computed optimal log position.
However, some problems exist in the existing systems. Firstly, the entire geometry of the log is not computed, and consequently, the log-scan of the front face of the log is not necessarily representative of the entire length of the often longitudinally irregular log. Thus, even if the log is rotated to obtain an optimized log position according to the front face of the log, the overall yield from the log may not be optimal. Also, although a certain optimal log position is computed and the log turning apparatus is controlled to rotate the log according to the desired position, the effective real position of the log may not be exactly as desired, since the log may react in an unforeseen manner while it is rotated, and it may accidentally be positioned differently from the computed optimal position.